I don't know why the build for multest failed (it compiled fine for me on both the bts/0.5.3 tag and the various latest commits of the devshares branch over the past week) but it should not affect the client if the rest compiled properly. The last things that get built at the end of the make command are a bunch of test programs that are stored in the tests/ directory within your build folder. You don't need them for the client to function.